The problem with tragedies waiting to happen is that, eventually, they do happen. For the 30-year-old hairdresser Claire Squires, it was a consuming desire to reach the finishing line, no matter what, in the 2012 London Marathon to raise thousands of pounds for the Samaritans. In the final stretch, she collapsed and died of cardiac failure which, an inquest has heard, was likely to have been brought on by a mixture of extreme exertion and an amphetamine-style supplement, DMAA, which she had put in her water bottle.

DMAA, or “1,3-dimethylamylamine”, may have been subsequently banned, but the market in sports supplements – those associated with body-building in particular – remains vibrant. According to Euromonitor, sales of sports nutrition supplements now exceed £200 million. It is testament to an increasingly toxic quest, especially among young people, for athletic and physical perfection. And they’ll snap up anything that makes that quest more achievable, even though much of it remains largely untested and, on occasion, dangerous. The top sellers include protein powders, bars, gels and capsules, mostly peddled to those who crave impressive pecs. And it’s unnecessarily expensive: a chicken sandwich and a glass of milk provides half the recommended protein intake for the average chap (around 56g, or 45g for women). Most of us eat more protein than we need, anyway.

But more pertinent is the fact that extra protein does not equal extra muscle. In the opinion of the British Nutrition Foundation, high-protein diets are “erroneously associated with fitness training because of the mistaken belief that this leads to greater strength, since muscle itself is protein”.

If that doesn’t persuade you to step away from the rowing machine, then perhaps you should ponder these statistics, collated for a 2011 NHS report, as you pound the treadmill: a US study of 15 protein powders found them to be laced with heavy metals such as cadmium, arsenic, mercury and lead; some dietary supplements marketed as being safer than those containing anabolic steroids (which mimic the effects of testosterone) contain substances associated with liver damage, stroke, kidney failure and pulmonary embolism (blockages in the artery in the lung).

These dangers are exacerbated by the fact that the products are flogged as foods rather than medicines, and that they are increasingly sold over the internet, still a pharmaceutical Wild West. Online pharmacies operating on the fringes of legality tend not to lose sleep over the welfare of faceless customers; the tills can never ring too loudly. So, supplements are aggressively served up on websites alongside aspirational messages such as “Fuel your ambition”. On one, a suggested meal plan for aspiring body-builders contained no fewer than six separate servings of its protein-building products throughout the day.

Behind these issues, though, lies a profound question: what’s it all for? Why do young men feel the need to bulk up and look buff? They are not only heading to the gym to enhance their body image but also to the operating theatre: in 2011, the number of men having abdominoplasty – a tummy tuck – rose by 15 per cent. Even the removal of “man boobs” is growing in popularity: 790 men were thus de-chested in 2011. It cannot be to attract the opposite sex – just as I’ve never met a man who’d choose a size eight waif over a girl with curves, I’ve never met a woman who dreams of being swept up by a man with rippling biceps and a rock-hard chest.

Perhaps we can blame society’s supposed idea of human beauty, reflected back at us from every magazine stand. Thin, airbrushed women with unsettlingly childlike faces jostle for attention alongside thick, oiled torsos topped by gleaming teeth. These are purveyed as images not only of beauty but also of success. This is what successful people look like: they nibble salad, wear Prada, work out, show discipline.

If you are in any doubt about the “beauty = success” equation, then seek out a book called Beauty Pays by Daniel Hamermesh. It’s a guide to the new discipline of pulchronomics, the study of how being better looking leads to being better off. Hamermesh, who gaily describes himself as no Alec Baldwin, finds the equation almost Einsteinian in its incontestability: the beautiful are more likely to find employment, get paid more, and have more attractive and highly educated spouses. Handsome men earn around 13 per cent more than uglier colleagues; prettier women either earn more or have richer husbands.

It is, Hamermesh insists, nothing short of discrimination against the plain, a fact that we silently acknowledge every time we doll up for a job interview. Isn’t it time we stepped away from this particular treadmill?